SqlNode sn_a = join.getLeft() ;
SqlNode sn_b = right.getLeft() ;
SqlNode sn_c = right.getRight() ;
SqlExprList conditions = new SqlExprList(join.getConditions()) ;
conditions.addAll(right.getConditions()) ;
Set<SqlTable> tables_ab = sn_a.tablesInvolved() ;
tables_ab.addAll(sn_b.tablesInvolved()) ;
SqlExprList newCond_ab = new SqlExprList() ; // Goes to new join(A,B)